New EDM Machines Offer Improved Precision, Greater Flexibility

October 25, 2018

Kosmo Machine recently purchased state-of-the-art wire and sinker Electrical Discharge Machines. “We’re really excited about these two new EDMs,” says Pat Smook, the company’s Vice-President of Sales. “They’re allowing us to complete even more complicated designs for our clients while at the same time offering unprecedented precision and repeatability.” The machines can be used to cut plate profiles and are popular in the tool and die industry.

The Fanuc Robocut x-C600iB Wire EDM is surrounded by a large tank, which rapidly fills with water. As a positively charged copper wire burns through a workpiece made of conductive metal, white sparks illuminate the area. Tiny bubbles of water carry away the microscopic shavings.

“The Fanuc offers positional accuracy of about 1/10,000 of an inch—about 1/30 the thickness of a single piece of hair,” he says. The six-axis machine offers great flexibility. “We can make a slot opening that expands in the piece and turns into a round hole. Or we can make a hole that is round on one side and square on the other. We can also do tapering.”

VIDEO// Fanuc Robocut x-C600iB Wire EDM in Action

Nearby, the new Mitsubishi Electric EA12S Advance Sinker EDM uses graphite or tungsten-copper alloy electrodes. These custom-made shapes are introduced to a positive electrical current. As the electrode approaches the workpiece, the tank is elevated and automatically fills with dielectric fluid.

Power settings are managed utilizing the patented “Fuzzy-Logic” system, which allows for automatic monitoring of conductivity and electrode gap distance. “This combination creates the ultimate control in dimensional stability while minimizing electrode wear,” says Smook.

The moving column sinker designer provides standard X, Y and Z-axes to 5 micron accuracy. To meet even more stringent requirements, Kosmo added a C-axis rotation. “With this rotation option, we can easily burn curved holes or what some call `port hole’ machining,” he says.

As an example of this, he points to an electrode on a table nearby. The piece has an unusual passageway—a hole that starts on top, goes straight down, then turns a corner and comes out the side.

The machine’s new Orbit-Pro System also assures more consistent side wall and bottom finishes and minimizes electrode usage—which translates to lower costs for the customer.

VIDEO// Mitisubishi Electric EA 12S Advanced Sinker EDM in Action

Both machines are noted for their ability to bore through extremely hard materials. They are used to create carbide wear parts as well as those made of titanium, tool steel, nickel alloys and tungsten—anything that’s electrically conductive.

“They may cost 10 times more than other parts, but they will last 50 times longer,” he says.

Kosmo’s aerospace, shipbuilding and advanced fiber clients appreciate the durability—and ultimately, the cost savings—of the EDM parts. “You don’t want to spend time shutting down the machine to keep changing that part that wears the most. It’s not just the cost of the part, it’s the assembly time,” he explains.

Guided by Computer Aided Engineering—using nano interpolation to compute position commands in nanometers—the EDMs are also valued for their precision and superior levels of tolerance; that is, their ability to duplicate parts within a slim margin of error. The wire EDM, for instance, can replicate parts to within one-ten thousandth of an inch, says Smook. “That is mind-bogglingly close tolerance.”

Cutting conditions are constantly monitored and cutting speeds are automatically increased using the Fanuc’s Flexible Discharge Pulse Control. “Many of our customers appreciate how small feature accuracy is improved through this feature, leading to more accurate geometry and straighter walls,” he says.

The model creates workpieces with improved corner accuracy and smoother transitions. “The age-old challenge of `approach control’ has been engineered to the point that entrance and exit witness marks are dramatically reduced,” he says.

Once the workpieces are completed on the EDM machines, they undergo a video inspection and are certified by Kosmo’s quality management system, which meets ISO 9001:2015 and AS9100D standards. The system covers all the manufacturing work centers in the plant.

“We can inspect everything we make,” says Smook. “A lot of shops can make parts, but they can’t inspect them.”

With the controls in place, “our customers hardly ever see a product that is out of specification. We take great pride in our acceptance rate over 99.9%. Together with an on-time delivery rate of over 94%, those are the best measurements of how well our system works.”

If you would like to learn more about the new features of these machines, and see them in action, please watch our videos.

Established in 1976, Kosmo Machine Inc. is a full-service precision machine shop specializing in CNC milling and turning, EDM machining and custom welding processes. Kosmo’s quality management system meets ISO 9001:2015 and AS9100D standards. The family-run business is devoted to quality production and superior customer service. Kosmo is located at 500 Trampton Rd, Sandston, Va. 23150. For more information or to request a quote, please call us at (804) 326-6819 or toll-free at (877) 798-1383, or visit our website, KosmoMachine.com.

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Kosmo Machine was recently featured in the Richmond Times-Dispatch. Here is a link to the article, click here.